The present invention relates to a memory package system for effecting the data communication between a reader/writer unit and a memory module in a contactless manner using electromagnetic induction coupling and, more particularly, to a memory package system which can effect communications using a simple and small-sized coil structure.
Hitherto, as a data communication system using electromagnetic induction coupling, for instance, a system as shown in FIG. 1 has been known (see U.S. Pat. No. 4,855,994).
As shown in FIG. 1, a reader/writer unit 10 is provided with a controller 12 for outputting a read access command, a write access command, a bit transfer request, and data (1 or 0). Transmission data which is transmitted from the controller 12 to a memory module 20 is frequency modulated by a modulating circuit 14 and amplified by an amplifier 16 and, thereafter, is supplied to a transmitting coil 18.
A receiving coil 22 is provided in the memory module 20 so as to confront the transmitting coil 18 of the reader/writer unit 10. A reception signal induced in the receiving coil 22 is rectified and regulated by a power source circuit 24 and is used as an internal power source. The reception signal of the coil 22 is also demodulated into a data bit by a demodulating circuit 26 and is applied to a memory controller 28.
When the memory controller 28 receives the write access command from the reader/writer 10 unit, the memory controller enables a non-volatile memory 30, thereby allowing write data, which is sent subsequently to the write access command, to be written into a designated address in the memory 30.
On the other hand, when the read access command is received from the reader/writer 10 unit, the memory controller 28 reads out the data stored in the address of the memory 30 which was designated by the read access command. Then, the memory controller sends the readout data to a multiplexer 36 on a bit-by-bit basis at every bit transfer request from the reader/writer 10 side unit. The multiplexer 36 switches its output between frequencies f.sub.1 and f.sub.2 of sine wave oscillators 32 and 34 in correspondence to the data bit 1 or 0 and is transmitted to the reader/writer 10 side unit through a transmitting coil 40.
At the reader/writer 10 unit, the transmission signal from the memory module 20 is received by a receiving coil 42 and amplified by an amplifier 44. Thereafter, the amplified signal is demodulated to the original data bit 0 or 1 by a filter 46 and is input to the controller 12.
However, in such a conventional memory package system for executing data communication using electromagnetic induction coupling, the power source circuit does not include back-up capabilities and a relatively large amount of electric power is required to transmit data from the memory module to the reader/writer unit. Therefore, even when data is transmitted from the memory module to the reader/writer unit, a power source transmission signal must be also sent from the reader/writer unit to the memory module.
Consequently, two sets of induction coils are necessary to communicate between the reader/writer unit and the memory module and two induction coils wound around an E-type core must be provided at two positions of a package of the memory module. Thus, the surface area of the package increases by the amount of the areas where two coils are arranged, thus presenting and there is a problem in that the memory module cannot be miniaturized.